The corrosion behavior of sputter-deposited amorphous Al-Cr-Mo alloys in 1 M HCl

Molybdenum additions have been made to enhance the passivity of Al-Cr alloys prepared by a sputter-deposition method. The corrosion behavior of amorphous Al-Cr-Mo alloys in 1 M HCl solution has been investigated by corrosion tests and electrochemical measurements. The addition of molybdenum to Al-Cr alloys decreases the anodic current density and makes the open circuit potential more noble. The amorphous Al-Cr-Mo alloys are passivated spontaneously even in 1 M HCl, while the open circuit potentials of Al-Cr binary alloys are in the active region even if a large amount of chromium is added. The addition of molybdenum to Al-Cr alloys, therefore, decreases the corrosion rate. The molybdenum addition is also effective in making the pitting potential more noble. The passive current density of Al-Cr-Mo alloys is lower than the anodic current density of sputter-deposited amorphous Al-Mo alloys. Consequently, the addition of molybdenum to Al-Cr alloys is effective in enhancing the corrosion resistance.